Electric lamp and method of manufacture thereof



W. J. GEIGER maze, 1938.

2,115,575 ELECTRIC LAMP AND METHOD of MANUFACTURE avian-1&0?

' Original Filed March 13, 1936 Fig.5.

- Inventor:

.WaWe-r' J., Geiger;

His Attovn'eg.

Patented Apr. 26, 1938 UNITED STATES ELECTRIC LAMP AND METHOD or MANU- FAC'I'URE THEREOF Walter J. Geiger, Cleveland Heights, Ohio. as-

signor to General Electric Company, a corporation of New York Original application March 13, 1936, Serial No .v

Divided and this application July 22, 1937, Serial No. 155,061

e Claims. (01. 176-7) My invention relates to electric lamps and more particularly to improvements in methods of manufacture thereof having as their object the production of lamps having their filaments or other light sources in uniformly accurate relation and alignment to their bases or portions thereof. The present application is a division of my application Serial No. 68,699, filed March 13, 1936.

Lamps are made at the present timewith bulbs having basing shoulders against which the bases are seated, thereby locating thebases definitely with respect to the bulbs. If the shoulders are crooked or if the filament is not properly located in the bulb, the said filament will not be properly located with respect to.the base. Hence .while this method serves very well for the. ordinary large lamps, it has disadvantages for the manufacture of lamps to be used for projection purposes where reflectors or other light-concentrating means are employed andthe light source must bear a definite relation to the said reflector or other means. The positive seating of the lamp bulb against the ,base is necessary with present basing methods the base it would necessitate having the base filled almost completely with cement since the cement would run down away from the bulbupun heating. This in turn would interfere with the 35 feeding of the lead wires through the base and would therefore be impractical for production work.

One of the objects of -my invention is to provide a lamp design and method of basing which 40 will overcome the above-mentioned disadvantages. Another object is to make possible the basing of a lamp with the base above the bulb without the base being butted directly against the bulb. Another object is to so construct the bulb and base 45 as to make possible a shifting and'rocking of the bulb with respect to the base prior to the cementing thereof so that the base can be accurately located in a predetermined position with respect to the light source in the bulb. Further advan- 50 tages and features of my invention will appear from the following description of species thereof. In the drawing, Fig. 1 is'an elevation of a lamp bulb and a base in section, the parts being so pro-'- portionedas to permit relative adjustment thereto thefilament in the bulb; Fig. 2 is an elevation, partly in section, showing the united base and bulb and a portion of apparatus for holding the parts during basing; Fig. 3 is an elevation, partly in section, of a completed lamp located in a re- 5 fiector; and Fig. 4 is an elevation, partly in section, of a lamp having a modified bulb shape.

Referring to the drawing, the particular lamp illustrated is of the butt-sealed miniature type used, for example, in flash lights. The lamp 10 in Figs. 1-3 comprises a bulb lp having a reduced cylindrical neck portion II and, preferably. afurther reduced portion l2 to which is sealed an exhaust tube l3. A pair of leading-in wires l4, l5 have portions thereof sealed in the joint 15 formed by the bulb I0 and exhaust tube l3. A filament I6 is mounted. on the leading-in wires I4, [5 which are held in spaced relation within the bulb by a bead ll of insulating material. In

order to accurately locatethe filament IS in a 2 =predetermined position in the bulb, one of the leading-in wires (I5) is preferably extended at I8 to a hollow tip l9 at the end of the bulb, as shown and claimed in U. S. Patent 1,983,362,

9 The base comprises a cylindrical metal shell .2I having at its rear end a body of insulating material 22, preferably glass, having an opening 23 therein and a metal eyelet 24 fused to the end thereof. The front end of the base shell 2| has an integral annular flange 25 turned outwardly therefrom. The said base shell 2l is partially filled with a ring of cement 26. The leading-in wire I5 is threaded through the opening 23 and the wire it through a slot 21 at the front of the base shell. The internal diameter of the base shell 2| is slightly larger than the diameter of the reduced neck portion ll of the bulb Ill to permit rocking and shifting of the bulb in the base.

For accurately locating the base, the bulb is held by vacuum in a movable chuck 28 while the base 20 is held above the bulb in a holder 29 comprising a metal support plate 30 having an opening it for the bulb Ill and an annular seating shoulder 32 around the upper end of said opening. The flange 25 on the base shell 2| is held in the said shoulder 32 by one or more radially movable spring members 33. The leads l4, l5 are then connected to a source of current supply so as to project an image or images of the filament 16 upon a screen and the chuck 28 is moved upor down or sideways to shift or tilt the bulb III in the base v2|! until the filament i6 is properly located at a predetermined distance and in a predetermined plane with respect to the as flange 25. The neck portion II is made of sufficient length to permit adjustment of the bulb into or out of the base without causing the base to abut against the shoulder 34 formed by the said reduced neck portion II. The entire bulb could of course be made the same diameter as the neck portion II thus entirely eliminating the shoulder 34. In other words, while in some cases a part of the inner surface at the front end of the base shell 2! may be in contact with the neck portion H in order to properly align the filament, the front end of the base in no event abuts against any part of the bulb.

After the correct optical positioning of the filament, the base shell 2| is heated, either by direct gas flame or by means of an electric resistance coil surrounding it,to cure the cement 26. During the baking operation, the cement expands and tends to flow down through the clearance between the base shell 2| and bulb neck I I. However, as it approaches the end of the base shell, the cement is hardened because the flange 25 and the end of the shell are kept cool by the comparatively heavy metal support plate 30 with which the said flange is in contact. Actually the cement just begins to flow into the said clearance when it is hardened. If a base without a flange were used, as for example, one having the conventional bayonet pins or other form of outwardly extending projection, the front end of the base adjacent the bulb should be cooled to secure the same effect. This cooling is an important feature of my invention.

After the cement has hardened, the lamp is completed by trimming the leading-in wires H,

l5 and soldering them to the base shell 2| and eyelet 24 as shown at 35 and 36 respectively in Fig. 3. The completed lamp is shown in Fig. 3.

mounted in a reflector 31 having an annular recess or boss 38 which is engagedby the base flange 25 thereby accurately locating the filament [6 with respect to the focus of said reflector.

The lamp shown in Fig. 4 has a modified bulb shape in that the cylindrical bulb ID has an enlarged bulbous or spherical neck portion H of end of said base.

slightly smaller diameter than the base shell 2|,

thereby permitting considerable rocking ot the bulb within the base to adjust the filament IS with respect to the flange 25.

Obviously my invention is not limited to the butt-sealed type of lamp shown in the drawing. It is also not essential to have a continuous flange 25 on the base. Instead, a plurality of lugs or wings may be formed from the base shell or bayonet pins may be substituted therefor.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of basing an electric lamp comprising a bulb containing a light source and having a neck portion and a base having an internal diameter slightly larger than that of the said bulb neck which consists in placing the base having a ring of .cement on the inside thereof over the neck of said bulb with the base uppermost, adjusting said bulb with respect to said base until the light source is deflnitely located with respect to a portion of said base, and heating a portion of said base to bake the cement therein while maintaining the end portion of the base adjacent the bulb relatively cool to harden the cement and prevent its flowing out through said 2. The method of basing an electric lamp comprising a bulb containing a light source and having a neck portion and a base having an internal diameter slightly larger than that of the said bulb neck which consists in placing the base having a ring of cement on the inside thereof over the neck of said bulb with the base uppermost, adjusting said bulb with respect to said base until the light source is deflnitely located with respect to a portion of said base, and heating a portion of said base to bake the cement therein while holding the end portion of the base adjacent the bulb in a metal holder to maintain it relatively cool so as to harden the cement and prevent its flowing out through said end of said base.

WALTER J. GEIGER. 

